Author Question: If a glass of water is on a table with a piece of paper under it, it is relatively easy to pull the ... (Read 26 times)

Mr. Wonderful · **on:** Jul 28, 2018

If a glass of water is on a table with a piece of paper under it, it is relatively easy to pull the paper out without disturbing the glass very much if the pull is done very quickly. This is because with a quick pull:
a. the force on the glass will be less.
b. the momentum of the paper will be greater.
c. the time for the pull will be less.
d. the coefficient of kinetic friction will be less.

Question 2

A proton moving at 6.0 104 m/s is projected at an angle of 30 above a horizontal plane. If an electric field of 400 N/C is acting down, how long does it take the proton to return to the horizontal plane? (Hint: Ignore gravity. mproton = 1.67 10-27 kg, qproton = 1.6 10-19 C)
a. 7.8 10-6 s
c. 7.8 10-7 s
b. 1.6 10-6 s
d. 3.9 10-6 s